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1da177e4
LT
1/* $Id: fault.c,v 1.122 2001/11/17 07:19:26 davem Exp $
2 * fault.c: Page fault handlers for the Sparc.
3 *
4 * Copyright (C) 1995 David S. Miller (davem@caip.rutgers.edu)
5 * Copyright (C) 1996 Eddie C. Dost (ecd@skynet.be)
6 * Copyright (C) 1997 Jakub Jelinek (jj@sunsite.mff.cuni.cz)
7 */
8
9#include <asm/head.h>
10
11#include <linux/string.h>
12#include <linux/types.h>
13#include <linux/sched.h>
14#include <linux/ptrace.h>
15#include <linux/mman.h>
16#include <linux/threads.h>
17#include <linux/kernel.h>
18#include <linux/signal.h>
19#include <linux/mm.h>
20#include <linux/smp.h>
1da177e4
LT
21#include <linux/interrupt.h>
22#include <linux/module.h>
1eeb66a1 23#include <linux/kdebug.h>
1da177e4
LT
24
25#include <asm/system.h>
1da177e4
LT
26#include <asm/page.h>
27#include <asm/pgtable.h>
28#include <asm/memreg.h>
29#include <asm/openprom.h>
30#include <asm/oplib.h>
31#include <asm/smp.h>
32#include <asm/traps.h>
1da177e4
LT
33#include <asm/uaccess.h>
34
1da177e4
LT
35extern int prom_node_root;
36
37/* At boot time we determine these two values necessary for setting
38 * up the segment maps and page table entries (pte's).
39 */
40
41int num_segmaps, num_contexts;
42int invalid_segment;
43
44/* various Virtual Address Cache parameters we find at boot time... */
45
46int vac_size, vac_linesize, vac_do_hw_vac_flushes;
47int vac_entries_per_context, vac_entries_per_segment;
48int vac_entries_per_page;
49
50/* Nice, simple, prom library does all the sweating for us. ;) */
51int prom_probe_memory (void)
52{
53 register struct linux_mlist_v0 *mlist;
54 register unsigned long bytes, base_paddr, tally;
55 register int i;
56
57 i = 0;
ccc34028 58 mlist= prom_meminfo();
1da177e4
LT
59 bytes = tally = mlist->num_bytes;
60 base_paddr = (unsigned long) mlist->start_adr;
61
62 sp_banks[0].base_addr = base_paddr;
63 sp_banks[0].num_bytes = bytes;
64
65 while (mlist->theres_more != (void *) 0){
66 i++;
67 mlist = mlist->theres_more;
68 bytes = mlist->num_bytes;
69 tally += bytes;
70 if (i > SPARC_PHYS_BANKS-1) {
71 printk ("The machine has more banks than "
72 "this kernel can support\n"
73 "Increase the SPARC_PHYS_BANKS "
74 "setting (currently %d)\n",
75 SPARC_PHYS_BANKS);
76 i = SPARC_PHYS_BANKS-1;
77 break;
78 }
79
80 sp_banks[i].base_addr = (unsigned long) mlist->start_adr;
81 sp_banks[i].num_bytes = mlist->num_bytes;
82 }
83
84 i++;
85 sp_banks[i].base_addr = 0xdeadbeef;
86 sp_banks[i].num_bytes = 0;
87
88 /* Now mask all bank sizes on a page boundary, it is all we can
89 * use anyways.
90 */
91 for(i=0; sp_banks[i].num_bytes != 0; i++)
92 sp_banks[i].num_bytes &= PAGE_MASK;
93
94 return tally;
95}
96
97/* Traverse the memory lists in the prom to see how much physical we
98 * have.
99 */
100unsigned long
101probe_memory(void)
102{
103 int total;
104
105 total = prom_probe_memory();
106
107 /* Oh man, much nicer, keep the dirt in promlib. */
108 return total;
109}
110
111extern void sun4c_complete_all_stores(void);
112
113/* Whee, a level 15 NMI interrupt memory error. Let's have fun... */
114asmlinkage void sparc_lvl15_nmi(struct pt_regs *regs, unsigned long serr,
115 unsigned long svaddr, unsigned long aerr,
116 unsigned long avaddr)
117{
118 sun4c_complete_all_stores();
119 printk("FAULT: NMI received\n");
120 printk("SREGS: Synchronous Error %08lx\n", serr);
121 printk(" Synchronous Vaddr %08lx\n", svaddr);
122 printk(" Asynchronous Error %08lx\n", aerr);
123 printk(" Asynchronous Vaddr %08lx\n", avaddr);
124 if (sun4c_memerr_reg)
125 printk(" Memory Parity Error %08lx\n", *sun4c_memerr_reg);
126 printk("REGISTER DUMP:\n");
127 show_regs(regs);
128 prom_halt();
129}
130
131static void unhandled_fault(unsigned long, struct task_struct *,
132 struct pt_regs *) __attribute__ ((noreturn));
133
134static void unhandled_fault(unsigned long address, struct task_struct *tsk,
135 struct pt_regs *regs)
136{
137 if((unsigned long) address < PAGE_SIZE) {
138 printk(KERN_ALERT
139 "Unable to handle kernel NULL pointer dereference\n");
140 } else {
141 printk(KERN_ALERT "Unable to handle kernel paging request "
142 "at virtual address %08lx\n", address);
143 }
144 printk(KERN_ALERT "tsk->{mm,active_mm}->context = %08lx\n",
145 (tsk->mm ? tsk->mm->context : tsk->active_mm->context));
146 printk(KERN_ALERT "tsk->{mm,active_mm}->pgd = %08lx\n",
147 (tsk->mm ? (unsigned long) tsk->mm->pgd :
148 (unsigned long) tsk->active_mm->pgd));
149 die_if_kernel("Oops", regs);
150}
151
152asmlinkage int lookup_fault(unsigned long pc, unsigned long ret_pc,
153 unsigned long address)
154{
155 struct pt_regs regs;
156 unsigned long g2;
157 unsigned int insn;
158 int i;
159
160 i = search_extables_range(ret_pc, &g2);
161 switch (i) {
162 case 3:
163 /* load & store will be handled by fixup */
164 return 3;
165
166 case 1:
167 /* store will be handled by fixup, load will bump out */
168 /* for _to_ macros */
169 insn = *((unsigned int *) pc);
170 if ((insn >> 21) & 1)
171 return 1;
172 break;
173
174 case 2:
175 /* load will be handled by fixup, store will bump out */
176 /* for _from_ macros */
177 insn = *((unsigned int *) pc);
178 if (!((insn >> 21) & 1) || ((insn>>19)&0x3f) == 15)
179 return 2;
180 break;
181
182 default:
183 break;
184 };
185
186 memset(&regs, 0, sizeof (regs));
187 regs.pc = pc;
188 regs.npc = pc + 4;
189 __asm__ __volatile__(
190 "rd %%psr, %0\n\t"
191 "nop\n\t"
192 "nop\n\t"
193 "nop\n" : "=r" (regs.psr));
194 unhandled_fault(address, current, &regs);
195
196 /* Not reached */
197 return 0;
198}
199
200extern unsigned long safe_compute_effective_address(struct pt_regs *,
201 unsigned int);
202
203static unsigned long compute_si_addr(struct pt_regs *regs, int text_fault)
204{
205 unsigned int insn;
206
207 if (text_fault)
208 return regs->pc;
209
210 if (regs->psr & PSR_PS) {
211 insn = *(unsigned int *) regs->pc;
212 } else {
213 __get_user(insn, (unsigned int *) regs->pc);
214 }
215
216 return safe_compute_effective_address(regs, insn);
217}
218
219asmlinkage void do_sparc_fault(struct pt_regs *regs, int text_fault, int write,
220 unsigned long address)
221{
222 struct vm_area_struct *vma;
223 struct task_struct *tsk = current;
224 struct mm_struct *mm = tsk->mm;
225 unsigned int fixup;
226 unsigned long g2;
227 siginfo_t info;
228 int from_user = !(regs->psr & PSR_PS);
83c54070 229 int fault;
1da177e4
LT
230
231 if(text_fault)
232 address = regs->pc;
233
234 /*
235 * We fault-in kernel-space virtual memory on-demand. The
236 * 'reference' page table is init_mm.pgd.
237 *
238 * NOTE! We MUST NOT take any locks for this case. We may
239 * be in an interrupt or a critical region, and should
240 * only copy the information from the master page table,
241 * nothing more.
242 */
243 if (!ARCH_SUN4C_SUN4 && address >= TASK_SIZE)
244 goto vmalloc_fault;
245
246 info.si_code = SEGV_MAPERR;
247
248 /*
249 * If we're in an interrupt or have no user
250 * context, we must not take the fault..
251 */
252 if (in_atomic() || !mm)
253 goto no_context;
254
255 down_read(&mm->mmap_sem);
256
257 /*
258 * The kernel referencing a bad kernel pointer can lock up
259 * a sun4c machine completely, so we must attempt recovery.
260 */
261 if(!from_user && address >= PAGE_OFFSET)
262 goto bad_area;
263
264 vma = find_vma(mm, address);
265 if(!vma)
266 goto bad_area;
267 if(vma->vm_start <= address)
268 goto good_area;
269 if(!(vma->vm_flags & VM_GROWSDOWN))
270 goto bad_area;
271 if(expand_stack(vma, address))
272 goto bad_area;
273 /*
274 * Ok, we have a good vm_area for this memory access, so
275 * we can handle it..
276 */
277good_area:
278 info.si_code = SEGV_ACCERR;
279 if(write) {
280 if(!(vma->vm_flags & VM_WRITE))
281 goto bad_area;
282 } else {
283 /* Allow reads even for write-only mappings */
284 if(!(vma->vm_flags & (VM_READ | VM_EXEC)))
285 goto bad_area;
286 }
287
288 /*
289 * If for any reason at all we couldn't handle the fault,
290 * make sure we exit gracefully rather than endlessly redo
291 * the fault.
292 */
83c54070
NP
293 fault = handle_mm_fault(mm, vma, address, write);
294 if (unlikely(fault & VM_FAULT_ERROR)) {
295 if (fault & VM_FAULT_OOM)
296 goto out_of_memory;
297 else if (fault & VM_FAULT_SIGBUS)
298 goto do_sigbus;
299 BUG();
300 }
301 if (fault & VM_FAULT_MAJOR)
1da177e4 302 current->maj_flt++;
83c54070 303 else
1da177e4 304 current->min_flt++;
1da177e4
LT
305 up_read(&mm->mmap_sem);
306 return;
307
308 /*
309 * Something tried to access memory that isn't in our memory map..
310 * Fix it, but check if it's kernel or user first..
311 */
312bad_area:
313 up_read(&mm->mmap_sem);
314
315bad_area_nosemaphore:
316 /* User mode accesses just cause a SIGSEGV */
317 if(from_user) {
318#if 0
319 printk("Fault whee %s [%d]: segfaults at %08lx pc=%08lx\n",
320 tsk->comm, tsk->pid, address, regs->pc);
321#endif
322 info.si_signo = SIGSEGV;
323 info.si_errno = 0;
324 /* info.si_code set above to make clear whether
325 this was a SEGV_MAPERR or SEGV_ACCERR fault. */
326 info.si_addr = (void __user *)compute_si_addr(regs, text_fault);
327 info.si_trapno = 0;
328 force_sig_info (SIGSEGV, &info, tsk);
329 return;
330 }
331
332 /* Is this in ex_table? */
333no_context:
334 g2 = regs->u_regs[UREG_G2];
335 if (!from_user && (fixup = search_extables_range(regs->pc, &g2))) {
336 if (fixup > 10) { /* Values below are reserved for other things */
337 extern const unsigned __memset_start[];
338 extern const unsigned __memset_end[];
339 extern const unsigned __csum_partial_copy_start[];
340 extern const unsigned __csum_partial_copy_end[];
341
342#ifdef DEBUG_EXCEPTIONS
343 printk("Exception: PC<%08lx> faddr<%08lx>\n", regs->pc, address);
344 printk("EX_TABLE: insn<%08lx> fixup<%08x> g2<%08lx>\n",
345 regs->pc, fixup, g2);
346#endif
347 if ((regs->pc >= (unsigned long)__memset_start &&
348 regs->pc < (unsigned long)__memset_end) ||
349 (regs->pc >= (unsigned long)__csum_partial_copy_start &&
350 regs->pc < (unsigned long)__csum_partial_copy_end)) {
351 regs->u_regs[UREG_I4] = address;
352 regs->u_regs[UREG_I5] = regs->pc;
353 }
354 regs->u_regs[UREG_G2] = g2;
355 regs->pc = fixup;
356 regs->npc = regs->pc + 4;
357 return;
358 }
359 }
360
361 unhandled_fault (address, tsk, regs);
362 do_exit(SIGKILL);
363
364/*
365 * We ran out of memory, or some other thing happened to us that made
366 * us unable to handle the page fault gracefully.
367 */
368out_of_memory:
369 up_read(&mm->mmap_sem);
370 printk("VM: killing process %s\n", tsk->comm);
371 if (from_user)
dcca2bde 372 do_group_exit(SIGKILL);
1da177e4
LT
373 goto no_context;
374
375do_sigbus:
376 up_read(&mm->mmap_sem);
377 info.si_signo = SIGBUS;
378 info.si_errno = 0;
379 info.si_code = BUS_ADRERR;
380 info.si_addr = (void __user *) compute_si_addr(regs, text_fault);
381 info.si_trapno = 0;
382 force_sig_info (SIGBUS, &info, tsk);
383 if (!from_user)
384 goto no_context;
385
386vmalloc_fault:
387 {
388 /*
389 * Synchronize this task's top level page-table
390 * with the 'reference' page table.
391 */
392 int offset = pgd_index(address);
393 pgd_t *pgd, *pgd_k;
394 pmd_t *pmd, *pmd_k;
395
396 pgd = tsk->active_mm->pgd + offset;
397 pgd_k = init_mm.pgd + offset;
398
399 if (!pgd_present(*pgd)) {
400 if (!pgd_present(*pgd_k))
401 goto bad_area_nosemaphore;
402 pgd_val(*pgd) = pgd_val(*pgd_k);
403 return;
404 }
405
406 pmd = pmd_offset(pgd, address);
407 pmd_k = pmd_offset(pgd_k, address);
408
409 if (pmd_present(*pmd) || !pmd_present(*pmd_k))
410 goto bad_area_nosemaphore;
411 *pmd = *pmd_k;
412 return;
413 }
414}
415
416asmlinkage void do_sun4c_fault(struct pt_regs *regs, int text_fault, int write,
417 unsigned long address)
418{
419 extern void sun4c_update_mmu_cache(struct vm_area_struct *,
420 unsigned long,pte_t);
421 extern pte_t *sun4c_pte_offset_kernel(pmd_t *,unsigned long);
422 struct task_struct *tsk = current;
423 struct mm_struct *mm = tsk->mm;
424 pgd_t *pgdp;
425 pte_t *ptep;
426
427 if (text_fault) {
428 address = regs->pc;
429 } else if (!write &&
430 !(regs->psr & PSR_PS)) {
431 unsigned int insn, __user *ip;
432
433 ip = (unsigned int __user *)regs->pc;
434 if (!get_user(insn, ip)) {
435 if ((insn & 0xc1680000) == 0xc0680000)
436 write = 1;
437 }
438 }
439
440 if (!mm) {
441 /* We are oopsing. */
442 do_sparc_fault(regs, text_fault, write, address);
443 BUG(); /* P3 Oops already, you bitch */
444 }
445
446 pgdp = pgd_offset(mm, address);
447 ptep = sun4c_pte_offset_kernel((pmd_t *) pgdp, address);
448
449 if (pgd_val(*pgdp)) {
450 if (write) {
451 if ((pte_val(*ptep) & (_SUN4C_PAGE_WRITE|_SUN4C_PAGE_PRESENT))
452 == (_SUN4C_PAGE_WRITE|_SUN4C_PAGE_PRESENT)) {
453 unsigned long flags;
454
455 *ptep = __pte(pte_val(*ptep) | _SUN4C_PAGE_ACCESSED |
456 _SUN4C_PAGE_MODIFIED |
457 _SUN4C_PAGE_VALID |
458 _SUN4C_PAGE_DIRTY);
459
460 local_irq_save(flags);
461 if (sun4c_get_segmap(address) != invalid_segment) {
462 sun4c_put_pte(address, pte_val(*ptep));
463 local_irq_restore(flags);
464 return;
465 }
466 local_irq_restore(flags);
467 }
468 } else {
469 if ((pte_val(*ptep) & (_SUN4C_PAGE_READ|_SUN4C_PAGE_PRESENT))
470 == (_SUN4C_PAGE_READ|_SUN4C_PAGE_PRESENT)) {
471 unsigned long flags;
472
473 *ptep = __pte(pte_val(*ptep) | _SUN4C_PAGE_ACCESSED |
474 _SUN4C_PAGE_VALID);
475
476 local_irq_save(flags);
477 if (sun4c_get_segmap(address) != invalid_segment) {
478 sun4c_put_pte(address, pte_val(*ptep));
479 local_irq_restore(flags);
480 return;
481 }
482 local_irq_restore(flags);
483 }
484 }
485 }
486
487 /* This conditional is 'interesting'. */
488 if (pgd_val(*pgdp) && !(write && !(pte_val(*ptep) & _SUN4C_PAGE_WRITE))
489 && (pte_val(*ptep) & _SUN4C_PAGE_VALID))
490 /* Note: It is safe to not grab the MMAP semaphore here because
491 * we know that update_mmu_cache() will not sleep for
492 * any reason (at least not in the current implementation)
493 * and therefore there is no danger of another thread getting
494 * on the CPU and doing a shrink_mmap() on this vma.
495 */
496 sun4c_update_mmu_cache (find_vma(current->mm, address), address,
497 *ptep);
498 else
499 do_sparc_fault(regs, text_fault, write, address);
500}
501
502/* This always deals with user addresses. */
503inline void force_user_fault(unsigned long address, int write)
504{
505 struct vm_area_struct *vma;
506 struct task_struct *tsk = current;
507 struct mm_struct *mm = tsk->mm;
508 siginfo_t info;
509
510 info.si_code = SEGV_MAPERR;
511
512#if 0
513 printk("wf<pid=%d,wr=%d,addr=%08lx>\n",
514 tsk->pid, write, address);
515#endif
516 down_read(&mm->mmap_sem);
517 vma = find_vma(mm, address);
518 if(!vma)
519 goto bad_area;
520 if(vma->vm_start <= address)
521 goto good_area;
522 if(!(vma->vm_flags & VM_GROWSDOWN))
523 goto bad_area;
524 if(expand_stack(vma, address))
525 goto bad_area;
526good_area:
527 info.si_code = SEGV_ACCERR;
528 if(write) {
529 if(!(vma->vm_flags & VM_WRITE))
530 goto bad_area;
531 } else {
532 if(!(vma->vm_flags & (VM_READ | VM_EXEC)))
533 goto bad_area;
534 }
535 switch (handle_mm_fault(mm, vma, address, write)) {
536 case VM_FAULT_SIGBUS:
537 case VM_FAULT_OOM:
538 goto do_sigbus;
539 }
540 up_read(&mm->mmap_sem);
541 return;
542bad_area:
543 up_read(&mm->mmap_sem);
544#if 0
545 printk("Window whee %s [%d]: segfaults at %08lx\n",
546 tsk->comm, tsk->pid, address);
547#endif
548 info.si_signo = SIGSEGV;
549 info.si_errno = 0;
550 /* info.si_code set above to make clear whether
551 this was a SEGV_MAPERR or SEGV_ACCERR fault. */
552 info.si_addr = (void __user *) address;
553 info.si_trapno = 0;
554 force_sig_info (SIGSEGV, &info, tsk);
555 return;
556
557do_sigbus:
558 up_read(&mm->mmap_sem);
559 info.si_signo = SIGBUS;
560 info.si_errno = 0;
561 info.si_code = BUS_ADRERR;
562 info.si_addr = (void __user *) address;
563 info.si_trapno = 0;
564 force_sig_info (SIGBUS, &info, tsk);
565}
566
567void window_overflow_fault(void)
568{
569 unsigned long sp;
570
571 sp = current_thread_info()->rwbuf_stkptrs[0];
572 if(((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
573 force_user_fault(sp + 0x38, 1);
574 force_user_fault(sp, 1);
575}
576
577void window_underflow_fault(unsigned long sp)
578{
579 if(((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
580 force_user_fault(sp + 0x38, 0);
581 force_user_fault(sp, 0);
582}
583
584void window_ret_fault(struct pt_regs *regs)
585{
586 unsigned long sp;
587
588 sp = regs->u_regs[UREG_FP];
589 if(((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
590 force_user_fault(sp + 0x38, 0);
591 force_user_fault(sp, 0);
592}